package com.hmdp.service.impl;

import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.CACHE_SHOP_KEY;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {
        //解决缓存穿透
        //Shop shop = cacheClient.queryWithPassThrough(CACHE_SHOP_KEY,id,Shop.class,this::getById,CACHE_SHOP_TTL,TimeUnit.MINUTES);

        //互斥锁解决缓存击穿
        //Shop shop = queryWithMutex(id);

        //逻辑过期解决缓存击穿
        Shop shop = cacheClient.queryWithLogical(CACHE_SHOP_KEY,id,Shop.class,this::getById,20L, TimeUnit.SECONDS);//方便测试
        if(shop==null) return Result.fail("店铺不存在!");

        return Result.ok(shop);
    }



    private static final ExecutorService CACHE_REBUILD_EXECUTOR= Executors.newFixedThreadPool(10);
//    public Shop queryWithLogical(Long id){
//        String key=CACHE_SHOP_KEY+id;
//        //1.从redis查询商铺缓存
//        String shopJson = stringRedisTemplate.opsForValue().get(key);
//        //2.判断是否存在
//        if(StrUtil.isBlank(shopJson)) {
//            //3.不存在，直接返回
//            return null;
//        }
//        //命中，需要把Json反序列化成对象
//        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
//        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
//        LocalDateTime expireTime = redisData.getExpireTime();
//        //判断是否过期
//        if(expireTime.isAfter(LocalDateTime.now())){
//            //未过期，直接返回店铺信息
//            return shop;
//        }
//        //已过期，需要缓存重建
//        //缓存重建获取互斥锁
//        String lockKey=LOCK_SHOP_KEY+id;
//        boolean isLock = tryLock(lockKey);
//        //判断是否获取锁成功
//        if (isLock){
//            //成功开启独立线程
//            CACHE_REBUILD_EXECUTOR.submit(() -> {
//                try {
//                    this.saveShop2Redis(id,20L);
//                } catch (Exception e) {
//                    throw new RuntimeException(e);
//                } finally {
//                    //释放锁
//                    unlock(lockKey);
//                }});
//        }
//
//        //没成功返回过期的商铺信息
//        return shop;
//    }
//    public Shop queryWithPassThrough(Long id){
//        String key=CACHE_SHOP_KEY+id;
//        //1.从redis查询商铺缓存
//        String shopJson = stringRedisTemplate.opsForValue().get(key);
//        //2.判断是否存在
//        if(StrUtil.isNotBlank(shopJson)) {
//            //3.存在，直接返回
//            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
//            return shop;
//        }
//        //命中的是否为空值
//        if(shopJson!=null){
//            return null;
//        }
//        //4.不存在，根据id查询数据库
//        Shop shop = getById(id);
//        //5.不存在，返回错误
//        if(shop==null){
//            //将空值写入redis
//            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
//            return null;
//        }
//        //6.存在，写入redis
//        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
//        //7.返回
//        return shop;
//    }
//    public Shop queryWithMutex(Long id){
//        String key = CACHE_SHOP_KEY+id;
//        //从redis查询商铺缓存
//        String shopJson = stringRedisTemplate.opsForValue().get(key);
//        //判断缓存是否命中
//        if(StrUtil.isNotBlank(shopJson)){
//            //命中则直接返回数据
//            return JSONUtil.toBean(shopJson, Shop.class);
//        }
//        //判断是否是缓存穿透
//        if(shopJson!=null){
//            return null;
//        }
//        //实现缓存重建
//        //1.获取互斥锁
//        String lockKey=LOCK_SHOP_KEY+id;
//        try{
//            boolean isLock = tryLock(lockKey);
//            //2.判断是否获取成功
//            if(!isLock) {
//                //3.失败，则休眠并重试
//                Thread.sleep(50);
//                queryWithMutex(id);
//            }
//            //4.成功，根据id查询数据库
//            Shop shop = getById(id);
//            //5.不存在，返回错误
//            if(shop==null){
//                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
//                return null;
//            }
//            //6.存在，写入redis
//            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL,TimeUnit.MINUTES);
//            return shop;
//        }catch(InterruptedException e){
//            throw new RuntimeException(e);
//        }finally{
//            unlock(lockKey);
//        }
//    }

    //    private boolean tryLock(String key){
//        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", LOCK_SHOP_TTL, TimeUnit.MINUTES);
//        return BooleanUtil.isTrue(flag); //为防止程序在拆箱的时候出现空指针，要手动拆箱
//    }
//
//    private void unlock(String key){
//        stringRedisTemplate.delete(key);
//    }
//    public void saveShop2Redis(Long id, Long expireSeconds) throws InterruptedException {
//        //1.查询店铺数据
//        Shop shop = getById(id);
//        Thread.sleep(200);
//        //2.封装逻辑过期时间
//        RedisData redisData=new RedisData();
//        redisData.setData(shop);
//        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
//        //3.写入redis
//        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY+id,JSONUtil.toJsonStr(redisData));
//    }
    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id=shop.getId();
        if(id==null){
            return Result.fail("店铺id不能为空！");
        }
        //1.更新数据库
        updateById(shop);
        //2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY+shop.getId());
        return Result.ok();
    }
}

